11 April 2011 DIS 2011

Deep Inelastic and Deep Exclusive Results from Jefferson Lab

Keith GriffioenCollege of William & Mary

griff@physics.wm.edu

Deep Inelastic Scattering 2011Newport News, Virginia

11 April 2011

11 April 2011 DIS 2011 2

Introduction

•The only thing we can measure is a cross section.•But by separating kinematics from nucleon structure, we can identify robust, experimentally determined objects, the structure functions:

•Thus, FT, FL, g1, g2(x,Q2) can be extracted for all x, Q2.•Experiment tells us where these can be interpreted in terms of parton distribution functions in pQCD and where complications show up.

•PDFs are known only through model fitting of structure functions.

•More so for transverse momentum dependent distributions and generalized parton distributions

11 April 2011 DIS 2011

JLab Kinematic Coverage

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Jefferson Lab Halls

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Hall A

Hall B

Hall C

Hall A

Hall BHall B

Hall C

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JLab Talks @ DIS2011★WG1PS2: Jeff Owens Uncertainties in determining the d quark PDF at large values of x ★WG1PS2: Slava Tkachenko Model independent extraction of neutron structure functions from deuterium data★WG1PS7: Peter Monaghan First Extraction of FL Moments from World Data★WG1PS7: Ibrahim Albayrak ... Deuteron FL ... and Extractions of the Deuteron and Non-Singlet Moments★WG1PS9: Silvia Pisano Results and Achievements at CLAS★WG1PS9: Simona Malace Quark-hadron duality★WG1PS10: Patricia Solvignon The nuclear dependence of R=σL/σT in Deep Inelastic Scattering★WG2PSVM: Valery Kubarovsky Vector-mesons production and DVCS at JLab ★WG4SINS: Hayk Hakobyan Quark propagation and hadron formation in the nucleus★WG4SINS: Sergio Anefalos Pereira Strangeness production in CLAS ★WG6PSH1: Vincent Sulkosky Neutron spin sum rules and spin polarizabilities at low Q2 ★WG6PSH1: Hovhannes Baghdasaryan Preliminary proton spin asymmetry results from SANE ★WG6PSH2: Nilanga Liyanage Moments of the neutron g2 structure function and ... higher-twist effects★WG6PST2: Jin Huang Measurement of double spin asymmetry ALT ★WG6PST3: Hamlet Mkrtchyan The quark-parton model and low-energy factorization studies ...★WG6PST3: Sucheta Jawalkar Spin azimuthal asymmetries on longitudinally polarized proton ★WG6PST3: Wes Gohn Beam single spin asymmetries in SIDIS from an unpolarized proton ★WG6PST4: Kalyan Allada Single spin asymmetry results from neutron ★WG6PST4: Aram Kotzinian SIDIS in target fragmentation region★WG6PST4: Todd Averett Target single spin asymmetry measurements ★WG6PSTV: Marco Mirazita Lambda polarization in electroproduction at CLAS ★WG6PSHP1: Yohann Perrin Coherent deeply virtual Compton scattering off helium (CLAS) ★WG6PSHP1: Andrey Kim Studies of exclusive processes with a longitudinally polarized target★WG7PS3:Dave Gaskell, Xin Qian, Yelena Prok, Javier Gomez, Francois-Xavier Girod, Gordon D. Cates 12 GeV

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Inclusive DIS

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Hall C Measurements of FL

E04-110 proton E00-002, Deuteron

★WG1PS7: Peter Monaghan First Extraction of FL Moments from World Data★WG1PS7: Ibrahim Albayrak ... Deuteron FL ... and Extractions of the Deuteron and Non-Singlet Moments

• Rosenbluth separation of FL and FT

• Moments require data at all x, including the resonance region

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Hall C Duality Averaging

Hall CChristy

★WG1PS9: Simona Malace Quark-hadron duality

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Hall C Moments of FL

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★WG1PS7: Peter Monaghan First Extraction of FL Moments from World Data

Cornwall-Norton Moments

Preliminary

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Hall C Determination of R

E99-118p,d targets Q2=0.1-1.7 GeV2

Measure of R=FL/FT

★WG1PS10: Patricia Solvignon The nuclear dependence of R=σL/σT in Deep Inelastic Scattering

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BoNuS: d(e,e’ps)X

Bound Nucleon Structure Experiment using CLASe’

n

p

!"d

p

X

e

(ν,q)

ps

★WG1PS2: Slava Tkachenko Model independent extraction of neutron structure functions from deuterium data

Detect the spectator proton from deuterium following en scattering. Make kinematic corrections using the spectator proton’s energy Es and momentum ps.

θpq > 100o

70 < ps < 100 MeV/cEbeam = 4 & 5 GeV

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BoNuS Results for F2n

•First data from a ‘free’ neutron target

•Black line (right) is Bosted/Christy model

•Black lines (below) are the CTEQX errors band

★WG1PS2: Slava Tkachenko Model independent extraction of neutron structure functions from deuterium data

Malace (red)from D

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Global PDF fits at JLab

CTEQ-JLab (CJ) collaborationAccardi, Christy, Keppel, Melnitchouk, Monaghan, Morfin,

Owens, Zhu

★WG1PS2: Jeff Owens Uncertainties in determining the d quark PDF at large values of x

•Focus on large-x, small-Q2 region- fully exploit SLAC and JLab data- reduced PDF uncertainty at large x

•Flexible d-quark parametrization-extract d/u ratio at x→1

•Large nuclear uncertainty-d-quark (and gluons)!-need BONUS12, MARATHON, PV-DIS

•Polarized PDFs:-New JLab Theory/Experiment initiative-Use current & future data over extended x & Q2 range

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g1 Data w/o CLAS

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g1 Data w/ CLAS

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★WG7PS3:Yelena Prok

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CLAS g1 Moments

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scaling: lnQ2

higher twist: (1/Q2)n

target mass corrections

χPT: (Q2)n

dominating resonances

Jefferson Lab @ 6 GeV explores the transition from DIS to χPT

★WG7PS3:Yelena Prok

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Higher Twist in Moments

Osipenko et al, PRD71(05)054007Polarized Nachtmann moments

CLAS data make moments possible

Osipenko et al, NPA845(10)1Nachtmann moments for 12C

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Hall C SANE★WG6PSH1: Hovhannes Baghdasaryan Preliminary proton spin asymmetry results from SANE

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Hall C SANE

Very

Prelim

A180 A80

Q2 = 1.7 GeV2

Q2 = 2.5 GeV2

Q2 = 3.5 GeV2

★WG6PSH1: Hovhannes Baghdasaryan Preliminary proton spin asymmetry results from SANE

xx

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Hall C EMC Effect

• Recent data from JLab are very precise.

• Slope with respect to x is used to characterize the strength of the effect

• 9Be anomaly is used to argue for a local-density origin of the effect

• Seely et al, PRL103(09)202301

slope

0.01 0.1 1 10Q2(GeV/c)2

0

0.005

0.01

d2n

MAID 2007Lattice QCDpQCD evolutionSLAC 155xJLab E99-117 (comb.)JLab E94-010JLab RSSThis work

P. Solvignon et al., in preparationPrelimin

ary

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Hall A g2n

•higher twist coefficient -0.01

0

0.01

0.02

!2

JLab E94-010: res. onlyJLab E94-010: res.+el.JLab E94-010: BCJLab E01-012: res. onlyJLab E01-012: res.+el.JLab E01-012: BCJLab RSS: res. onlyJLab RSS: BCSLAC E155x: BC

0.5 1 2 4x

-0.01

-0.005

0

0.005!

2 (D

IS)

BBGRSVAACLSSJLab E94-010JLab E01-012JLab RSS

~ WW

Prelim

inary

P. Solvignon et al, in preparation

•Burkhardt-Cottingham Sum Rule

•Γ2WW is sum of g2WW for W>2 GeV Q2

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Semi-Inclusive DIS

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Differential Cross Section Bacchetta, et al., JHEP 2(2007)093 Unpolarized and Longitudinally polarized

AUL = {UL terms} / {UU terms}

ALL = {LL terms} / {UU terms} = Higher Twist

0

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Differential Cross Section Bacchetta, et al., JHEP 2(2007)093 Transverse target polarizations

= Higher Twist0 at high Q2

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TMDs and Fragmentation

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The observables are the structure functions such as FsinφUL, not the transverse

momentum distributions (TMDs) or fragmentation functions (FFs). Four-fold differential data in x, z, Q2 and PT are essential to allow modeling of TMDs and FFs.

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CLAS ALU

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• Mher Aghasyan et al., E01-113 in preparation for publication• CLAS data for AULπ°

• Unpolarized liquid hydrogen target• Beam energy of 5.776 GeV• Q2>1; 0.4 < z < 0.7

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CLAS ALU

CLAS, Avakian et al, PRC69(04)042201

ALUsinϕ

• CLAS data from E1f run period (2003)• Unpolarized liquid hydrogen target• Longitudinal beam polarization of 75%• Beam energy of 5.498 GeV

HERMES, Airapetian et al, PLB648(07)164

★WG6PST3: Wes Gohn Beam single spin asymmetries in SIDIS from an unpolarized proton

Preliminary

Preliminary

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Asymmetries from eg1b

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Avakian et al., PRL105(10)262002

CLAS

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A1 ≈ g1/F1 for eg1-dvcs

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•eg1-dvcs data (25%) of total•PT dependence → µ0 ≠ µ2

•For π+, π- and π0

★WG6PST3: Sucheta Jawalkar Spin azimuthal asymmetries on longitudinally polarized proton

CLAS

CLAS

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AUL for eg1-dvcs

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The target spin asymmetries as a function of φ have both sinφ and sin2φ components.

AsinφUL (higher twist) is significant for π+, π0

Asin2φUL (leading twist) is small suggesting, like for eg1b and HERMES, that

the Collins favored and unfavored fragmentation functions are nearly equal and opposite.

★WG6PST3: Sucheta Jawalkar Spin azimuthal asymmetries on longitudinally polarized proton

CLAS

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E06‑010: TransversitySpokesepersons: J. P. Chen, E. Cisbani, H. Gao, X. Jiang,

J. C. Peng

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Beam Polarimetry(Møller + Compton)

LuminosityMonitor

•First measurement on n•Polarized 3He target

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Hall A E06-010 AUT

•Preliminary Collins/Sivers for n•5.9 GeV electron beam•Polarized 3He target•0.14 < x < 0.35•1.3 < Q2 < 2.7 GeV2

•Still working on systematic uncertainties

•Curves: diquark model (Ma), global fit (Anselmino), light-cone quark model (Pasquini)

AUT

Preliminary

★WG6PST4: Kalyan Allada Single spin asymmetry results from neutron

X. Qian, et al., in preparation

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Hall A ALT for the Neutron

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At leading twist:

Preliminary

★WG6PST2: Jin Huang Measurement of double spin asymmetry ALT

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xF < 0PΛ

measured ~ 0.3

xF > 0PΛ

measured ~ 0.

Preliminary

★WG6PSTV: Marco Mirazita Lambda polarization in electroproduction at CLAS

DIS Lambda Production

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DVCS and DVMP

sinϕ moments of ALU and AUL

are related to linear combinationsof generalized parton distributions

★WG2PSVM: Valery Kubarovsky Vector-mesons production and DVCS at JLab

suppressed

higher twist

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ρ0 DVMP @ CLAS

Morrow et al, EPJA39(09)5

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CLAS DVCS ALU

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DVCS Target SSA★WG6PSHP1: Andrey Kim Studies of exclusive processes with a longitudinally polarized target

CLASeg1-dvcs data

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DVMP Target SSA

•target fragmentation enhances

★WG6PSHP1: Andrey Kim Studies of exclusive processes with a longitudinally polarized target

CLAS neutral pions

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Conclusions

• Jefferson Lab has an intense program on:– unpolarized and polarized inclusive DIS– semi-inclusive DIS with pions– DVCS– DVMS with pions and rhos– using proton, deuteron, 3He, and nuclear targets

• Details of these topics can be found:– in the advertised talks at DIS2011

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